India, Dec. 27 -- More than 20% of groundwater samples tested in Delhi contained nitrate levels above the permissible limit of 45 mg/l, with some samples reaching up to 994 mg/l - over 22 times the safe standard - according to data submitted by the Central Groundwater Board (CGWB) to the National Green Tribunal (NGT).

With a peak reading of 994 milligrams of nitrates per litre of drinking water, Delhi fared as the fifth worst-affected state or Union territory for high nitrate contamination, according to the report.

Andhra Pradesh fared the worst in the country with nitrate levels touching a peak of 2,296 mg/l, it showed.

While 20.39% of Delhi's samples exceeded safe limits (eighth-worst among states and UTs), Rajasthan recorded the hig...